PHP Deprecated – php8.1 – OpenLiteSpeed – Litespeed Plugin

Hello,
I am using Openlitespeed server with php8.1 version and installed litespeed plugin. I checked litespeed’s debug log and discovered this message. Can you please tell me what that message is and how to fix it? Thank.

PHP Deprecated: Automatic conversion of false to array is deprecated in /usr/local/lsws/mydomain.com/html/wp-content/plugins/xml-sitemap-feed/models/functions.sitemap.php on line 133

code in line 133 is

function xmlsf_cache_get_archives( $query ) {

global $wpdb;

$key = md5($query);
$cache = wp_cache_get( 'xmlsf_get_archives' , 'general');

if ( !isset( $cache[ $key ] ) ) {
    $arcresults = $wpdb->get_results($query);
    $cache[ $key ] = $arcresults;
    wp_cache_set( 'xmlsf_get_archives', $cache, 'general' );
} else {
    $arcresults = $cache[ $key ];
}

return $arcresults;

}